Switching system



my n, w24@ J. C. FIELD SWITCHING SYSTEM .1.4 c, FIELD SWITCHING SYSTEMJuly l, 19% 1.499%@ Filed July 5, 1919 2 Sheets-Sheet 2 mog by MM A@Asystems for detecting the vpositioned groups ...y i, ieee.

NETE@ STATES,

insane tentant essie.. l

' JOSEPHC. FIELD, OF ORNGE, NEW JERSEY, ASSGNOR TO WESTERN ELECTRIC COM-PANY, INCORPORATED, OF NEW YORK,

N.Y., A CORPORATION OENEW YORK.

swrreiame SYSTEM.

appucation filed July 5,

To aZZ whom it may concern:

Be it lrnown'that I, JOSEPH C. FniLD, a residing at 432 Central Avenue,Orange, inthe county of Essex, State of New Jersey, have inventedAcertain new and useful Improvements in Switching Systems, of which thefollowing is a full, clear, concise, tion.

This invention relates to switching systems and particularly tol thoseemployed in presence of submarine or other marine vessels. In systems ofthis character, in which it is desired to selectively observelindividually or binaurally in pairs, the operation of fixedly ofsubmerged detectors I responsive to mechanical vibrations propagatedthrough the water from a submarine' or other source, it is desirable toprovide means for not only readily and quickly selecting such groups butalso to select the individual on paired detectors `within the groups forobservation.v Particularly in the binaural method of determining thelocation of a rapidly moving source of vibration by means of a system inwhich three or more 'detectors at each station are connected in diferentpairs to separate transmissionlines leading to' the binaural receiversat the observing station, it is necessary that the shifting between thepairs of detectors within a group vbe accomplished as rapidly as may bepossible. It is also often desirable to rapidly repeat the observationof'certain pairs of Adetectors composing the group at a selectedstation.

In some systems of this character it is 'desirable to binaurally observethe operation of diierently' spaced pairs of detectors. Since the designof the acoustic compensator often employed in such observation dependsupon the spacing of the paired detectors, it is desirable to providemeans insuring the use of the proper compensator'in each ca se.

In order to reduce the deleterious cohering y or packing effects uponthe microphonic detrical circuit, which effects are' caused by sparkingand, similar electrical disturbances incident to the sudden`applicationandrelmoval ofcurrent, such circuit-interrupting and exactdescripf- 1919. serial no. 308,759.

provide in a system of this' nature employ-4 ing differently spacedpairs of ldetectors, automatic switching means whereby the use of aproper acoustical lected pair is insured.

Another object of the invention resides in the rovision of meansinsuring that the microp onie detecting device is connected to anddisconnected from the operating circuit only during' periods when theelectrical conditions of the circuit are stabilized.

To attain thesey objects in accordance with a feature of the invention,electromechanical switching devices at the various detecting stationscapable of individual selection by alternating `eunrent impulsestransmitted from the observers .station are retained mechanically uponselection, the detector pairs thereat being selectively connected to thetransmission. lines leading to the binaural receivers at the observersstation by the transmission of additional reserved current impulses fromthe observers station. The selected switching device is maintained inits more advanned positions by virtue of direct current flowing throughits'winding, and upon the cessation of such current it returns to itsmechanically held selected position,

thus permitting the reselection of the pairsA compensator for 'a' se-vtors at the time such detectors are associated with or disassociatedfrom the circuits.

. These and other features not specilically mentioned above will clearlyappear from Ythe following specification and the annexed drawing, Figs.1 and 2 of which, when placed end to end with Fig. 1 at'the left, showone embodiment of the invention as applied to a multiple stationsubmarine de tection system, while Fig. 3 sho-Ws more in detail the typeof selector employed..

Referring to the drawing, at an observers station A there is provided areversing relay 3, controlled b v a plurality of multiply connectedsending devices 1, 2, 170 and 171. and a switch 48 tor impressing-reversed current impulses upon a phantom circuit composed of physicalpairs'of conductors 4-5 and 172-173 and simplexing coils 147 to 152inclusive and extending tothe other stations of the system. Seria'llyintercom. nected resistance 153 and condenser 154 are bridged acr'ossthe phantom circuit for the well known purpose of eliminating sparksproduced by the opening and closing of the' contacts of relay 3, whileresistance' 168 andV condenser 169 shunt the contacts ofthe Sendingdevices for a similar purpose- V VAsso,- ciated with the phantom circuitat the stations B and C and controlled by the sending devices and theswitch48, selectors 6 and 8 are provided to selectively associateswitclr. ing relays 10, 11, 12'and 13, 14, 15 respectively, With thephantom circuit controlling the association of the detectors 16, 17, 18andY 1 9, 20, 21 in the desired pair arrangements with the pairs ofconductors 4-5 and 172-"- 173. Selectors 7 and 9, provided at stationsliand'C respectively. are similar and also controlled b v the sendingdevices and the as sociated switch. selectively associate switch.

ing relays 22, 23, 24 and 25. 26, 27 with the phantom circuity tocontrol the individual association of the detectors 16. 17 and 18 withthe physical pairs of conductors 4-5 and 172-173 inpaired'arrange'mentwith corresponding ones of detectors 19, 2 0 and 21.Although the selectors 6. 7, 8 and 9 mav be ot any suitable step-by-steptype adaptedvto be advanced to a certain pointupon the receipt of apredeterminedseries ot' closely succeeding impulses of current from. theobservers station` the type disclosed in myPatent No. 1.343.256 datedJune 15, 1920, is preferable. The detectors 16vto'21 inclu; sive may beot' any suitable type responsive to mechanical vibrations propagatedthrough the water to cause variations vin electrical conditions ofanfassociated eircuit,and'm ay 29, 3()A and 31 to notify the observerregarding the station or pair ot' stations selected. This selector 28may be of a type similar to that employed for selectors 7,' 8 and 9arranged to be mechanically reta-ined in each of a plurality ofpositions, and the type dis-- closed in my Patent No. 1,343,256 datedJune 15, 1920, adjusted to be individually retained in a plurality ofpositions is preferable. Switching relay 82 is also controlled by theselector 28 to selectively' control the a'ssociation of the receiversot' binaural` observation sets X and Y ,with pairsof conductorsextending to the selected. detectors. 48 at the observers Astationcontrols the impression-ot reversed current impulses upon thephantolncircuit Jfor the selection of the Ypairs of detectors subsequentto the selection of the station or stations and, through the mediumofrelay 33, controls the supply ot current to the operating circuits ottheselected detectors. y

The binanral observers set X 'comprises ear-pieces 34 and 35 to whichsounds generjated by receivers 3 6 and 37, in response to 'currentvariations produced by detectors associated therewith, are conveyedthrough -adjustz'tblellength air tube 40 interposed lbetweenfixed-length tubes 39 and 43 respectively. The relative el'ectivelcngthsof air tubes 40 and 41 may be adjustably varied b v the shifting ort amovable stop member 4G in response to the rotation ot handwheel 411, theposition of such stop member being indicated by the pointer 45.l'linaural ob'- servation set Y corresponds with sot X e5- cept Jfor anincrease in the total length ot the adj ustable-length air tubes whichis necessary to agree with the increase in spacing between detectors atseparate stations as compared with detectors at the same station.

lt is thought .thatthe invention may l,

more readily comprehendcd from the tal-- lowingdescription of theoperation ol the system shown on the annexed drawings.

. Assuming that it is desired to binanrallv observe the response ofdctectorslG and 1S at station B. the observer operates the sendingdevicel for such station which is one of lthe vseveral multiplyconnected sending devices vadapted for selecting particular stations orpairs of stations.. The engagement ofspring 65- with wheel 66.responsive to the first movementof the sending device .1. ca iuses theoperation of relay 68 over a circuit extending from battery, through thewinding of relay 68, the normal contact of relay 6,9. the wheel''andthespriug 65 of the sending device 1. segment 49, and` switch arm 47 ofVswitch 48, ground. The closure of'tho alternate. Contact .of relay GS'bridges the winding of selector 28 in series with condenser-163 acrossthe phantom circuit while the opening of the normal ,contactthereotdisconnects .the source of curmember 181.

Aweaves rent from the switch arm 71 of such selector.' Each tooth of thesending device 1 engaging the spring closes contact 67, thereby.operating reversing .relay 3 over a circuit extending from battery,through the winding of relay 3,. contact 67 of sending device 1andsegmen't 49 and switch-arm 47 of switch 48 to ground. r1`hesucceeding open ing of contact 67 when the spring 65 leaves the tooth ofthe sendingdevice 1 releases relay 3.v Therefore, current impulses ot'alternating polarity are transmitted over the phantom circuit, selectors6, 7, 8, 9 and 28 each being advanced one step in response to each ofsuch impulses. Selector 6 being adjusted to be individually responsiveto the series of impulses transmitted by the sender 1, such selectorwill be retained mechanically in its advanced position with its Contactarm 72 within one step of-contact 7 B'upon the cessation of the series,while the other selectors at stations B and C will not be advanced tothe predetermined position. This can, itis thought, be morejclearlyunderstood from a brief description of the selector mechanism shown inFig. 3.

In this figure 175 and 176 designate the windings of an electromagnetcontrolling a centrally pivoted armature 177, which is adapted -to bepolarized by,a permanent magnet (not shown). vAttached to the armature177 is an elongated arm 178,carrying at its free end a pin 179 and at apoint intermediate its ends a pin 180. Both of these pins are arrangedto engage a pivoted lever 181 carrying at its upper end a stepping pawl182. The electromagnct together` ,with the lever 181 are carried by-asuitable sup port (not shown). There is also secured to this support aratchet Wheel 183 which i's mounted in close proximity to the steppingIpawl 182, whichis adapted, when actuated, to move into engagement withthe ratchet Wheel. lBy means of a spring 184 the ratchet wheel 183isretained in its normal position. The stepping pawl 182is nor-l mallyheld against a stop-pin 185 bythe action of a spring 186 attached at oneend to the paWl 182. and at the other to the pivot-ed The pins 179 and180 engage' the pivoted lever 181 upon opposite sidesof the pivoted axisand upon opposite faces in such a manner that with each movement of vthearmature 177 in either direction, the

stepping pawl 182 Will cause a one movement of the ratchet wheel 183.

Upon the shaft carrying the ratchet wheel 183 and movable therewith is aContact carrying arm 187, the free end of which is adapted to makecontact with contact springs 188, 189, and 190. This contact arm 187corresponds to the one shoivn `in `conjunction With the selectors 6, 7,8, 9, and 28. Carried by the ratchet wheel 183 is a holdstep ing member191 which-has one end formed `the free end of said holding spring, whichis provided with a bent projection, is in theA path of the member 191.

When the armature 177 moves in response to 'current impulses to thewinding-1'75-176 of the electromagnet, the lever 181k causes theengagement of the stepping paivl 182 with the ratchet wheel 183. Theratchet Wheel 183 is thereupon moved by current impulses 'through themagnet windings to a positionV which. inthis. particular case, is withingne step of contact 188, Where the holding spring 192 engages the member191. Thus iffthe current impulses are no longer transmitted, the ratchetwheel 183 will be retained in its advanced position by the holding sring 1-92.

From tlie above description it is at once seen that the selectors areadapted to be ad' vanced to a 'predetermined vpoint due to thetransmission of alternatingcurrent impulses, where they are adapted tobe mechanically held in their actuated position,

position. However, if the holding current is disconnected andthereby'ceases to traverse the Winding of the electromagnet of theselector, the selector will berestored to its mechanically held positionfrom which position it can again be advanced.

'In order to restore the selector to normal it is necessary to advancethe selector to a point where the holding spring 192 is no longer inengagement with the member 191. When this is done the holding -spring192 falls out of the path .of the member 191 and permits the selector tobe restored to normal under thev actionof the spring 184.

The selectorv 28 also responding to each impulse, advances in responseto the series until the switch-'arm 71 thereof rests upon cont-act 88,in which position the selector is mechanically retained.4

D ue to the disengagement of spring 65 from the Wheel 66, uponthecompletion of the series of impulses, relay 68 is released and by theopening of its alternate contact removes the Winding of selector 28 fromits bridged relation to the phantom circuit While the closure of itsnormal contact causes the lighting of lamp 29 over a circuit eX-tendingv from battery,- through the upper contact of relay 68,switch-arm 71 in engagement with contact 88, and the 'lamp 29 to ground,thereby indicating that station B has been selected.

The switch-arm 47 is then rotated in a clockwise direction and upon itsengagement with `segment 50, establishes an operating circuit for relay69 from battery, through the winding ot' relay 69, the segment 50,.andthe switch-arm 47 of switch 48 to ground. The opening of the normalcontact of relay '69 introduces another break in the circuit otrelay 68to prevent its false Aoperation during further selection, while theclosure of the alternate contact of such relay connects in shunt ofcondenser 70 a Aresistance 174, thereby transmitting oneadditionalvimpulse over the phantom circuit. Selector 6 is thereuponadvanced'one step causing its switch-arm 72 to engage contact 73 andthereby bridge relay 12 across the phantom circuit. The connecting ofresistance 174 in shunt of condenser 70 in this manner converts thenormally non continuous or inductive phantom circuit into a conductivephantom circuit suitable for the transmission thereover of directcurrent which causes the operation of relay 12. The. closure of contacts105 and 1,06 of relay 12 bridges detector 18 across conductors 4 and 5,while the closure of contacts 103 and 104 of such relay bridgesdetector16 across conductors 172 and 173. The subsequent engagement ofswitch-arm 47 with segment 62 operates -relay 33 over a circuitestablished from battery, through the winding` of ,relay 33, and segment62 and arm 47 .of switch 48 to ground. The closure of contact 162 ofrelay 33 completes an operating circuit for detector 16 from battery,through conductor 173, contact 103 of relay 12, the current-varyingdevice ot detector 16, cntact 104 of relay 12, conductor 172, contact162 of relfy 33 and lretardation coil 132 to the other side of battery.The closure of Contact 161 of relay 33 establishes a simi- -laroperating circuit for detector 18 extending from battery, throughconductor 4, contact 106 of relay 12, the current-varying device ofdetector '18, contact 105 or" relay. 12, the conductor 5contact 161 ofrelay 33 and retardation coil 131 to the other 'side of battery. Contact162 of relay 33 is shunted by' condenser 94 while contact 161A of suchrelay is shunted by condenser 03 to provide capacitance to absorb thesurges of current due to the opening and closing of the circuit.

The current-varying device operated by the vibrations of detector 16causes current variations to be transmitted over conductor 173, throughcondenser l91, contact 164 of relay 32, the winding of receiver 37 andreturning'over'condu'ctor172, while the current variations, due to thevibration ot detector 18, are transmitted over conductor 5, throughcondenser 92, contact 167 of relay 32, the winding of receiver 36 andreturning over conductor 4. rihe sounds produced in the receiver 36, inresponse to such variations, are transmitted through fixed length airtube 38, the adjustable length air tube 40, and the lix'ed length a'irtube 42 to ear piece While the sounds produced in receivcr 37 aretransmitted through fixed length air tube 39, adjustable length air tube41, and ixed'length air tube 43 to ear piece 35.

The observer then rotates the hand-wheel 44 causing variations in therelative lengths of the adjustable length airtubes-40 and 41 by theshifting of movable stop 46 until the sensation is received by theobserver when binaurally listening to the sounds emitted from ear pieces34 and 35 that the source of sound is straight ahead. The position ofthe pointer 45 relative to its associatediseale indicates. the angularrelation eristing beswitch 48 to ground, to send a single currentimpulse of reversed polarity over the phantom circuit for causing aone-step advancement of selector 6 and a consequent disengagement ofswitch-arm 72 and contact 73. Relay 12 is thereby released fordisconnecting vdetectors 16 and 18 from the pairs ot conductors 4v-5vand172 and 173, vrespectively. However, the contacts of all selectors arespaced so as to require a two-step advancement of the selector betweenthe disengagement of one contact and the engagement of the succeedingcontact. This interval is of advantage in permitting the'various relaysand other apparatus to function properly.- 4The switch-arm 47subsequently disengaging segmentl A60 releases relay 3, therebytransmitting another impulse of. current of reversed polarity over the.phantom circuit and a consequent one-step adthe conduct-ors 4 and4 5,while the closure of contacts 99 and 100 bridges detector 17 acrossconductors 172 and 173, respectively.

'vancement of selector 6 in which position Upon 'the engagement ofsegment 63 bythe switch-arm 47 relay 33 operates overa circuit lay 12.

established from battery, through the winding of relay 33, segment 63,and the arm v47 of l switch 48 to supply battery to the detectors 17 and18 as previously described for detectors 16 and 18, 4except that thecircuits in# clude the contacts of relay 1l insteadpf recase the soundspro\ As in the previous 36an'd 37 responsive duced in the receivers tothe vibrationsof detectors 18 and 17 re-v` spectively, may be observedand the ,binaural balance obtained through the agency of observation setX. After the corresponding scale-reading obtained in this case has beenobserved, the switch-arm 47 is y advanced to engage segment 64. Asv thearm 47 disengages segment 63, relay 33 is again released to remove thesource of current from the operating circuits of the connected detectorsas before, and when the arm engages segment61, relay 3 id again operatedover ya ,circuit extending from battery, through the winding of relay 3,and segment 61 and arm 47 of switch 48 toground.'

, Selector 6 in its one-step advancement,'in

response to the single impulse of current thereby transmitted overthfphantom circuit, causes arm 72 to disengage contact 74, releasingrelay 11 for disconnecting detectors 17 and 18 :from conductors 445 and172-173. ment of arm is released to current of 'reversed polar-ity'overthe phantom circuit. Selector 6 in making the one-` step advancement inresponse thereto, causes switch-arm 72 to engage contact, 75, and relay10 becoming bridged across the phantom circuit operates due to thedirect current flowing over such circuit. The closure of contacts 97 and98 of relay 10 bridges detector 17 across conductorsA 4 and 5, while theclosure of contacts 9 5 and 96 of such relay bridges detector 16 acrossthe condue tors 172 and 173. 'fhe engagement of `arm 47 with segment 64operates relay 33 over a circuit-established from battery through thewinding of relay 33 and segment' 64 and arm 47 of switch 3 to ground,completing operating circuits for tectors 16 and 18 except for thesubstitution of the contacts of relay 10 lfor those of relay 12. Asbefore, the sounds produced in receivers 36l and 37 in response to thevibrations of detectors 17 and 16 respectively, maybe observed' and thebinaural balance obtained by means of the set X.

After the corresponding scale-reading indicating the angular relation ofthe source of vibration to the base line joining detectors 16 and 17 hasbeen obtained, the arm 47 is advanced to its normal position in con--the ,windingof relay 68 with the Y adapted Ito Upon the subsequentdisengage- 47 from segment 461, relay transmit another impulse of'v'detectors 16 and 17 similar to those previously traced vfor de-v tactwith segment 49. As the arm disengages segment 64, relay 33v againreleases to remove` the battery supply' from donductors 4-5 and 1724173.When arm ,47 disengages'segment 50, relay y69 releases, thereby' 70-removing the shunt-circuit previously established for'condenser 70 andreconnecting i wheels 66 of the sending devices. Selector 6 is thereuponrestored toits selected mechanically held position with the arm 72within vone stepA of *contact 73 since the direct current path for suchselector is disabled by the removal of the shunt-circuit aroundcondenser 70. Therefore, if it is desired to reobserve the operation ofthe detectors at station B, the arm 47 is given another clockwiserotavtion with'the result as previously described.

, However, in case it is-neXty desired to subject the detectors atstat'ionC to observation, 85 ansender 171 similar to that shown at l'buti transmit a series of impulses which will release any Selectors havingbeen previously operated, is then actuated, relay 68 operating toreconnect the selector 28 with 9o the' phantom circuit, and aspreviously de scribed, reversed current impulses are transf mitted overthe phantom circuit. In re- ,sponse to this series, selectors 6 and 28advance step by step until the mechanisnrfor retaining them is disabledand they are restored to normal. The other selectors are also advancedstep by step but are restored `:xtovnormal upon the cessation of theimpulses. *Relay 68 is released upon the cessation of 10o thev impulsesto remove the selector 28 from its relation to the phantom circuit.

A sender 2 similar to 1 but adapted for selecting station C is' thenactuated, relay 68 operating to reassociate the-selector 28 with 105 thephantom circuit. This series of impulses causes selector 8 to advanceuntil its larm 80 is within one step of contact 81, in which positionsuch selector is individually retained by mechanical means as previouslyde- 11o scribed in connection-with Fig. 3,'whilese` lectors 6, 7. and 9are restored to normal. Selector 28 .also advances in a manner similarto. that described'in connection with the selection of station Bzto amechanically held position, wherein arm 71 is in engagement with Contact89. Due to the subsequent re-l lease of relay 68, selector 28 is removedfrom its association with the phantom circuit and lamp 30 is lighted toof station C. A s previously described, arm 47 of vswitch 48 is given aclockwise rotation .and its engagement with segment 50 operates relay 69to connect the resistance 174 in shunt of the condenser 70 to transmit a125 single impulse over the -phantom circuit, ad-

Voperates due to the direct current flowing 13o indicate theselectiou12o Y conductors .172 and' 17 3 respectively, while conductors 4 and 5,while the closure oflcon tactsv 123 and 124 bridges detector 21 across,conductors 172 and 173 respectively. The

subsequent engagement of arm47 with segment 62 causes the operation ofrelay 33 to supply battery to the current-varying devices of detectors19 and 21, as previously de scribed in connection with the detectors atstation. B. The detectors 19 and-21 arethen. 'subjected to binauralobservation by means of set X, as described for the other detectors, andafterithe position-of pointer 45, indicating the angular relation of thesourceV of vibration 'to a base linejoining detectors 19 and 21, isobserved, arm 47 is advanced to engage segment 63.. Relay33-releasesupon the disengagement of arm 47 from segment 62, therebyremoving current supply from the conductors 4--5 and 172 and 173respectively, while the subsequent engagement and disengagement of arm47 and segment 60', as before, transmits two reversed current im-vpulses over the phantom circuit advancing arm 80 of selector 8 to engagecontact 82.

Relay 15 is released upon the disengagement of arm 8O from contact 8 1,while relay 14` being bridged across the phantom circuit when arm 8Oengages. contact 82 operates upon the direct current iiowing over s uchcircuit. The closure of 'contacts 119 and 120 of relay 14 bridgesdetector 21 across the closure of contact '117' and 118 thereof bridgesdetector 2O acrossv conductors 4 and 5. As before, the subsequentengagement of arm 47 and segment 63 reoperates relay 33 to supplycurrent to the current-varying de5 vices of detectors 20 and 21. Theoperation of such detectors having been observed by set X in a mannersimilar to that described, arm 47 is advancedto engage segment 64. Asbefore, when arm 47 leaves segment 63, relay 33 releases removingcurrent supply from the observed detectors, and as the arm engages anddisengagessegment 61 two reversed current impulses are impressed uponthe phantom circuit causing a two-step advancement of selector 8, thearm of which advances to igage contact 83. Relay 14 releases when arm 80leaves contact 82, thereby disconnecting detectors 2O and 21 fromconductors 172 and 173 respectively and 4.-5 respectively, and relay 13operates due to direct current flowing over the phantom circuit when arm8O engages Contact 83. The closure of contacts 113 and 114 of relay 13bridgesdetector 19 across conductors 4 and 5, while the closure ofcontacts.

. 11.5 and 116 of such relay bridges detector 20 across conductors '172and 173 respec-l As in the previous instances, relayv .33 operates uponthe engagement of arm 47 tively.

and segment 64' to supply battery to the selected )detectors After thesedetectors have,

been subjected to binaural 'observation` through set Xin a mannersimilar to that previously described, the arm 47 is returned to 'itsnormal position in engagement with segment 49, thus releasing relay 33and subsequently 'releasing selector 8 by releasing relay 69for/disabling thedirect currentpath oveuthe phantom circuit.' #Selector8 therenpon returns to its mechanically retained po@ sition innwhich'arm 80 -is within onestep of contact 81. A Relay 13 also.releases to disconnect detectors 19 and 20 from the pairs 4-5 and 172'and 173 respectively. fore, the observer 'then actuates the releasingsender 171 to'transmit a series of impulses over the phantom circuit t ocause the release of selectors. 8 and 28 and restores all apparatus tonormal. 4

The observer thereupon actuate's sender 170 which Aisgadapte'd toimpress a series of impulses upon the phantom circuit to enable theobserver-to pair thedetectors atlstation B with those at station C. Asin the other cases,

'and 85 respectively. Selectors 6 and 8 also advance in response to 'theimpulses but not being adjustcd'for this series of impulses returntonormal uponl the cessation or' the series. However, master selector 28is advanced and is mechanically retained with its 1 arm 71 engagingcontact 90. Lamp 31 is lightedover an obvious circuit to indicate thatstations Band Chave been simultaneously selected and relay 32 isoperated over fa circuit established from battery, through the normalcontact of re'lay 68, the arm 71 of selector 28 in engagement withcontact 90, andthe-winding of relay 32 to ground. The

opening .of contacts 164 and 167 of relay 32 removes, receivers 36 and37 from their nor- 'mal association'yvith conductors 4-'5 and 172-173respectively, 'and the closure of contacts'165 and 166 of such relayassociates receivers 136, and pairs.

in a clockwise direction until it engages segmentv4 62. As previouslydescribed, the en- 1f37' with such conductor Arm' 47 vof switchistlire'uponrotated 12o gagement of arm .4`Ijwith segment 59A operatesrelay 69,'to thereby connect the resistance 174,. in shunt of condenser70, sending one impulse of'current over' the I'Jphantoml cir.-

cult and establishing a direct current path over the phantom' circuit.Selectors 7 and 9 simultaneously advance one step in response theretocausing arms 76 and 84 to engage contacts 77 and 85 respectively. Relays24 f and 27 being lthereby bridged across the I phantom circuit areoperated'by the direct i current in vsuch circuit, the closure ofcontacts llland 112 of relay 24 bridging detecto'r 18 at station Bacross conductors 172 and 173 and the closure -of contacts 129 andsequent engagement of arm 47 and segment 62 operates relay 33 to supplycurrent to the engage segment 64. Relay 33 releases to reselecteddetectors.

The angular relation of the source of sound to a base line joiningdetectors 18 and 21 is then obtained in a manner similar to thatpreviously described when the detectorsA were located at the samestation, except that binaural set Y is employed under these conditions,the current variations produced byv detector 18 flowing from conductor173 through condenser 91, contact 165 of relay 32, and the Winding ofreceiver 137 to con ductor 172, While the current variations produced bydetector 21 flow from conductor 5, through condenser 92, contact 166 ofrelay 32 and Winding vof receiver136 to conductor -4 The sounds producedin receiver 136 in response thereto are conveyed to ear piece 134,through serially interconnected air tubes 138, 140 and 142, While thoseproduced in receiver 137 are conveyed to ear piece 135, through seriallyconnected air tubes 139, 141 and 143. The movable stop member 146 isIthen adjusted through the agency of hand- Wheel 144 until thelobserver, listening binaurally-to sounds emitted from the ear pieces 134and 135, receives the sensation that the source of sound is straightahead.' The posivtion then. occupied byl the pointer 145 indicates theangular relation of the observed source' to a base line joiningdetectors 18 and 21.

The arm 47 is then moved to engage seg-` ment 63, the disengagement ofsegment 62 causing the release of'relay 33 to remove the current supplyfrom the' conductors 4 5 and 172 and 173 respectively and the subsequentengagement Vand disengagement of arm 47 and the segment'GO impressingt-Wo reversed current impulses upon the phantom` circuit, the iirst ofwhich causes selectors 7 and 9 to ,move arms 76 and 84 out of' en.

gagement With contacts 77 and 85 respectively. Relays 24 and 27consequently release to disconnect detectors 18`and 21 from conductors'172 and l173 respectively and 4 5. lThe second impulse causesselectors7' and 9 to move arms 76 and 84 into engagement with contacts78 'and 86- respectively. Relays 23 and 26 being thereby bridged acrossthe phantom circuit are operated by the direct current present in suchcircuit, the former relay through the closurecf its coni tacts 109 and110 bridging detector 17 across conductors 17 2 and 173 respectively andlthe latter relay through the closure of its contacts 127 and 128bridging detector 20 across conductors 4 and 5. As before, relay 33operates upon the engagement of arm 47 With l segment 63 to supplybattery to the selected detectors. After subjecting such detectors tobmaural observation through set Y, in a manner similar to thatpreviously described, y

and noting the angular relation of the source of vibration to the baseline'joining detectors 17 and 20, arm 47 is advanced to move batteryfrom conductors 4-5 and 172 and 173 respectivelyl when arm 47 disengagessegment 63 and the subsequentl engagement and disengagement of arm 47and segment -61 transmits two' reversed current impulses over'thephantom circuit. 1n ref sponse to the first 'of these impulses, arms 76and 84 disengage contacts 78 and 86 respectivel releasing relays 23 and26 to disconnect etectors 17 and 20-from conductors 172 and respectivelyand 4 5, While in response to the second impulse, such arms engagecontacts 7 9'and 87 respectively. Re-

lays 22 and 25being brid ed across the phantoml circuit are operated bythe direct current present therein, the vformer by the closure ofcontacts v107- and 108 bridging detector 16 across conductors 172 and1734respectively and the latter by the closure of contacts 125 and 126bridging detector 19 across conductors 4 and 5, The subsequentengagement of arm 47 and segment 64 oper-.

`Since the direct current path -over the Aphantom circuit is disabled bythe'release of re lay 69, selectors 7 arid 9 are returned to theirmechanically retained positions. The releasing sender 171'then beingactuated causes the releaseof selectors 7, 9 and 28 and the return ofall apparatus to normal.

Although only two selectable stations are shown, it is understood that'there may be, and usually are, many such stations em- 'ployed in asystem of this character.

It will be noted that in each instance the selectors are advanced byalternating currentimpu'lses transmitted over the phantom 'circuit andthat nocurrent is present in the 'operating circuits of the detectorsvuntil after the detectors are'connected in circuit.

Since the position of the larm 47 of the switch 3 determines the pairofA detectors connected to the line circuits, such arm may serve asmeans to `positively indicate the pair under observation, the normalposition lThe above table gives the number of' impulses required to betransmitted for cansing the advancement t the selectors in the.

order 6, 8,7 and 9 respectively to their me chanically 'held positionwhich, as brought out inthe specification, is within one step of theirst contact spring associated therewith.. The last set f impulses ineach of the groups listed in the above table is the number required toadvance the'selector 28 t'o such a position as to close a circuitincluding the signal lamp corresponding with .the selector selected at theselectable station.

The selector 28 will, therei'ore,'not cause the lighting of the signallampsl due to its advancement by the other impulses in the group. -A

What is claimed is:

. l.. In a switching system, a hantom circuit, normally' permitting onlythe passage of yalternating current, a selecting station and a pluralityof' selectable stations associatedtherewith, a stepby-step selectorateach se-v lectable station. responsive to alternating e aio currentimpulses received over4 the phantom ..circuit, means atthe selectingstation for transmitting alternating currentimpulses over the phantomcircuit, means responsive to said alternating current impulses foradvancing any selector into a predetermined position, means at theselecting station for ,adapting the circuit to permit the passage ofAdirect current, and additional means at the selecting station fortransmitting current impulses over the circuit when so adapted tooperate said second mentioned means for advancing the selected terminedposition.

2. In a switchingA system, a phantom circuit, a condenser includedtherein, a. select'- ing station and a plurality of selectable stationsconnected to the phantom circuit, a step-by-step selector atl eachselectable station responsive to alternating current impulses receivedover the phantom circuit and adapted to be held mechanically in apredeselector from its prede? termined position, means at the selectingstation for transmitting alternating currentr impulses' over the phantomcircuit, means reponsiveto said alternating current impulses foradvancing any selector into a predetermined mechanically retainedpositiommeans at the selecting station for shunting the condenser, andmeans als-at the selecting station for subsequently transmittingalternating current impulses over the phantom circuit for effecting theoperation of said second-mentioned means to advance the selectedselector from its predetermined position into a magnetically retainedposition.

"3. In a switching system, a phantom circuit, normally'permitting onlythe passage of alternating current` ap selecting station and a pluralityof selectable stationsv associated with the phantom circuit, a step-bystep selectorv atleach selectable station responsive to alternatingcurrent impulses r'e ceived over the phantom circuit, and adapted to bemechanically held in a'v predetermined position, a plurality ofelectrical devices atA each selectable station,vmeans at the selectingstation for transmitting alternating current impulses over `the phantomcir-v cuit, means responsive to said alternatingr current im ulses foradvancing any selector into `-a pre etermined mechanically retainedposition, means also atithe selecting station for converting the phantomcircuit into a conductive circuit 'adapted to.4 permit the passage ofdirect current, additional means at the selecting station fortransmitting current impulses over "the conductive phantom circuit toe'ect the operation of said second` mentioned means for advancing theselected selector Vfrom the predetermined position, said selectedselector being retained in its further advancedpositi'on under controlof the last-mentioned means, and Ameans controlled. by :the selector inits further advanced position to, selectively associate the electricaldevices thereat with the side 'circuits comprising the phantom circuit.

' 4. Ina switching system, apair of line l circuits, a receiving and aplurality ofselectable stations associated therewith, transx'mittingmeans at each of the selectable stations, switching means at thereceiving station, selecting means ateachof the select'- able stationscontrolled by said switching means for associating said transmittingmeans with the line circuits in one relation, additional means at theselectable stations line circuit in another relation, a plurality ofreceiving lmeans at the receiving station adapted for use with thetransmitting means in each relation, and selecting means controlled bythe switchingmeans for automatically associating with the .line circuitsthev receiving means adapted for use with the selecting 'relation of thetransmitting means.

5. In a switching system, a phantom circuit, a selecting and a pluralityof selectable stations associated therewith, a source of iio -alsocontrolled by said switching means for associating said transmittingmeans with the 1 Y impulses received overthe phantom circuit,

means at the selecting station for transmitwith the side circuits,

selectable stations into their predetermined- Vrality able station forassociation with the side circurrent for association with 4each sidecircuit comprising the phantom circuit, a plurality of receiving meansat`the selecting station for association with the side circuits, apluot' transmitting means at each selectcuits, a plurality ofstep-by-step selectors at each selectable station responsive to currentting current impulses over the phantom circuit for advancing anyselector into a predetermined position, means operated by the individualadvancement of one selector in response to suh current impulses to itspredetermined position to selectively associate a pair of the associatedtransmitting means and-nieans operated by the simultaneous advance ofsuch selec- .tors to their lpredetermined positions to each associateone of the associated transmitting meansv with one side circuit, the.transmitting means at the two stations being associated with differentside circuits, and means for selectively associating the receiving meanswith the side circuits.

6; In a switching system, a phantom circuit, a selecting station and apair off selectable stations associated therewith, a

source of current associated with each side of the phantom circuit, aplurality of pairs of receiving means at the selecting station forassociationwith the side circuits ofthe phantom, circuit', a pair ofltransmitting means at each selectable. station, a pair of step-by-step'selectors at each selectable station responsive to current impulseslreceived over the phantom circuit, a step-by-l step selector at theselecting station also responsive to such current impulses, controlmeans at the selecting station for transmitting current impulses overthe phantom circuit to individually advance one of the selectors ateither station into a predetermined position, additional control meansat the selecting station for transmitting current impulses over thephantom circuit. to

advance both of the other selectors at the positions, switching meanscontrolled by the first-mentioned selector for associating t-heassociated pair of transmitting means with the side circuits,simultaneously Operating switchingmeans at each selectable stationcontrolled by the other selector thereat in `its predetermined positionto associate one of the transmitting means thereat with One sidecircuit, the two transmitting means being associated with different.side circuits, and means controlled by the selector at the selectingstation to selectively associate a pair of receiving mean-s with theside circuits.

7 In a signaling system, a signaling cir.- cuit, a receiving station, aplurality vof groups of signal transmitters, a plurality of groups ofsignal receivers at the receiving station, means controlled by codeimpulses impressed upon tliccircuit to selectively associate thegroups-of transmitters with the circuit, and means at the receivingstation Aalso responsive to the code impulsesto control thev associationof the groups of receivers with the circuit.

8, In a signalingfsystem, a signaling cir-` receiving station, aplurality of cuitel a group vpf si nal transmitters, the transmitters wi-hin glie different groups being'dif'- fereln tly\imhterrelated, a groupof signal receivers a the receiving station for each of the groups ofsignal transmitters, means controlled by codeimpulses impressed upon`the circuit to selectively associate the groups of the transmitters withthe,A circuit, and means lat the receiving statioirl also responsive tothe code impulses to control the association of the vgroups 'ofreceivers with the circuit as determined by the relation of thetransmitters within the selected oup.

9. In a switching system, a pluralit of" circuits interconnecting a'plurality o selectable stations, selectors and selectable devices ateach station, means for operating said` selectors to select adeviceovercne of said circuits and means operative forL transmitting overanother of the circuits a se-v ries of impulsesv to selectively setaselector station controlled from said central station for selecting eachvof said selectable devices4 individually, whereby a plurality ofdevices at two or more substations may be selected.

simultaneously.

l1. In a switching system, a line 'circuit interconnecting a centralstation and a plu rality of substations, a plurality of selectabledevices at each substation, selecting means. controlled at said centralstation for selecting said devices in pairs, and additional selectingmeans controlled at Said central' station for selecting each of saiddevices individually.

12. In a switching system, av line'circuit. interconnecting a centralstation anda lurality of substations, a plurality of se ect-- abledevices at each substation, means controlled at said central station forselecting a pair of said devices at any substation, and additional meanscontrolled atsaid central station for simultaneously selecting any oneof' said devices ateach of two substations,

13.`In a switching system, a line circuit interconnecting a centralstation and a pluralityof siibstat-ions, a plurality of selectvabledevices at eachsub-station, selectingrv means controlled at saidcentralstation for associating said-devices in pairs with said line circuit,and additional selecting means controlled at said central station forasso- -ciating each 4of said devices individually trolled at saidcentral station for associating a pair of said devices at lanysubstation with said line circuit, and additional meanscontrolled atsaid central station for simultanei ously associatingl any one of saiddevices at each of two substations with said line cir- 15. In aswitching system, a phantom cire tional means controlled atsaid centralstation for, associating each of' said- Adevices 1ndividually with `theside circuits 'of the phan- 16. Ina switching system, a phantom cir-.cuit interconnecting'afcentral station and a plurality of substations,a plurality of selectable devices' at 'each substation, means controlledat said central station for asso- '4 ciating-a pair ofsaid' devices atany station with one side circuit ofthe phantom circuit, and additionalmeans controlled at said cen- Atral station for simultaneouslyassociating any one of said devices at each of'tw'o substations with oneside circuit of the phantom circuit, the two devices being associatedwith different side circuits.

17. In a switchingsystem, a line circuit,

a plurality ofelectrical devices, switching means for connecting saiddevices to the line circuit individually and. in pairs,.a source ofcurrent tor connect-ion to the line circuit, and means cooperating withthe switching means for limiting the connection of the source to theline ciicujt'and its'disconnection therefrom to periods when the deviceor devices' are connected thereto.

18. In .a switching system, a line circuit,

" a plurality of electrical devices for connection therewith, switchingmeans for connecting said devices to the line circuit individually or 1npairs, a source of current for conf nection to the line circuit, andmeans coopconnecting the sourcevfrom the line circuit prior to thedisconnection of the device or devices therefrom.

19. In a switching system, a phantom lcircuit, a plurality of.electrical devices, means tor selectively ,connecting said devicesindividually to opposite side circuits of said phantom circuit, a sourceof current adapted to be connected to said side circuits, and meanscool'ieratingwith said first mentioned means Yfor connecting said sourceof current to said side circuits only during the period when one of saidelectrical devices is con n'ectcd thereto.

20. In switching system, a phantom circuit, a plurality otelectricaldevices,switch-'- ing, meuns for connecting said devices inpairs to o ne side circuitlof said phantom circuita sourcefof currentfor connection to said side circuit, and means cooperating withsaid"switching means for connecting said source offcurrent to said circuitonly during the periods when said 4electrical devices are connectedtheretoi l 21. In switching system, a line circuit,

"an electrical device,stepbystep means for` connecting the device totheiine circuit, lja source of current for connectioii to theline icircuit` and means cooperatingfwitlrthe switching means forlimitingthecfincction o f the source to the lin'e circuit and itsdisconnection therefrom to device is connected thereto.

of selectable stations, a plurality of electrical devices at each ofsaid selectablestations, suf'itching'means for connectingv said devicesto saidline circuit, a source of current adapt# ed to be connected tosaid line circuit, and means cooperating with said switching means forconnecting said source of current to said' linecircuit only 'during theperiods when said electrical devices are connected to said line4circuit.

23. In a switching system, a line circuit normally permitting only thepassage of alternatingcurrent, a selecting station and a rpluralityotselectable stations associated therewith. means at the selecting stationforv transmitting alternate current impulses over the Aline circuit.,means at each selectable staperiods "when the 22. In`a switchingvsystem, a line'circiiitv interconnecting a setlecting and -a pluralityiio tion responsive to alternating currentv iinpulses received over theline circuit, means at the selecting station for adapting the ein ,cuitto permit the passage of direct current, and additional means at theselecting station for transmitting direct current impulses over thecircuit when so adapted't'o operate the said means located at theselectable station.

In witness whereof, I hereunto subscribe my name this 24th day of JuneD., 1919..

JOSEPH c. FIELD.

